Axial seals have been used for sealing lubricated track joints on endless tracks of track-type machines and radial lip seals have been used on loader linkage lubricated pin joints to seal the oscillating pins of the various linkages. In relatively clean environments, a small amount of inward radial load is required on the sealing lip to seal in the bearing lubricant. As the operating environment becomes dirtier and more severe, higher lip loads are required to ensure good sealability and to keep the abrasive contaminants away from the bearing surfaces of such hinge or pin joints.
The track bushings used in endless tracks of earthworking machines and the radial lip seals used in the pin joints of the loader linkages of earthworking machines present one of the most severe operating environments possible for these kind of seals. In such extremely severe applications, a very high axial force or an inwardly directed radial force is desirable to prevent highly abrasive contaminants such as mixture of sand, dirt and water from not only entering the joint itself, but from becoming lodged under the seal lip. Any contaminants lodged under the seal lip quickly grinds or wears a groove into the pin/bushing and/or the seal and quickly wears out the seal lip and consequently the pin/bushing. This wear mechanism is responsible for many early hour joint failures which is detrimental to the components of the joint and causes downtime for the machine in order to repair or replace the components.
It is desirable to produce a seal that maintains the supply of lubricant within the lubricated joint while providing a seal that extends the useful life of the sealed joint. Various researchers in the fields of lubrication, surface analysis, materials science, and solid mechanics have studied the sealing mechanisms that allow a lubricating film to exist between the seal lip and the oscillating or rotating shaft without allowing leakage. It is desirable to economically produce a seal that has a unique texture on the sealing surface that would prevent the penetration of the abrasive contaminants into the seal lip or seal surface while improving the lubricating ability of the joint.
The present invention is directed to overcoming one or more of the problems set forth above.